[AcWIng 799] 最长连续不重复子序列

#include<iostream>

using namespace std;
const int N = 1e5 + 10;
int a[N], s[N];

int main()
{
    int n, res = 0; 
    scanf("%d", &n);
    for (int i = 0; i < n; i ++)    scanf("%d", &a[i]);
    for (int i = 0, j = 0; i < n; i ++) {
        s[a[i]] ++;
        while (s[a[i]] > 1) {
            s[a[j]] --;
            j ++;
        }
        res = max(res, i - j + 1);
    }
    printf("%d", res);
    return 0;
}